(1) Field of the Invention
The present invention relates to a mobile track leveling, lining and tamping machine useful for work in track switches and tangent track, the track comprising two rails fastened to ties supported on ballast and each rail having a gage side and a field side, which comprises a machine frame mounted for mobility along the track in an operating direction and carrying drive, brake, operating energy source and operating control means, and two widely spaced undercarriages supporting the machine on the track, including a rear undercarriage in the operating direction. The machine has ballast tamping units mounted between the undercarriages and immediately preceding the rear undercarriage in the operating direction, the ballast tamping units being mounted for independent transverse and vertical adjustment with respect to the machine frame, a respective one of the ballast tamping units being arranged at the gage side and the field side of each rail, and each ballast tamping unit comprising a pair of vibratory tamping tools reciprocable in the direction of the track and immersible in the ballast with a respective one of the ties positioned between the tamping tools. A track leveling and lining unit is mounted on the machine between the two undercarriages and immediately preceding the ballast tamping units in the operating direction, the track leveling and lining unit comprising power-driven, transversely and vertically adjustable lifting hooks and flanged lining rollers operated by a leveling and lining reference control system.
(2) Description of the Prior Art
U.S. Pat. No. 4,627,360, dated Dec. 9, 1986, discloses such a compact track leveling, lining and tamping machine. Compact machines have been very successfully used because the coordinated arrangement of the ballast tamping units and the track leveling and lining unit spaced therefrom at a constant distance and arranged between two widely spaced undercarriages supporting the machine on the track results in a much more accurate track position correction than the previously used cantilevered construction, the relatively wide spacing of the undercarriages also producing a much less pronounced bending of the rails during the leveling and/or lining operation therebetween so that the rails are not subjected to unacceptable flexing forces. The machine disclosed in this patent comprises a machine frame carrying drive, brake, operating energy source and operating control means and the machine frame is supported for mobility along the track in an operating direction by two wide spaced undercarriages. Two ballast tamping units are mounted on vertical and transverse guides between the undercarriages for independent transverse and vertical adjustment with respect to the machine frame, and each unit comprises two pairs of vibratory tamping tools reciprocable in the direction of the track and immersible in the ballast with a respective tie positioned between the tamping tools, a respective pair being arranged at the gage side and the field side of each rail. A track leveling and lining unit is also mounted between the two undercarriages and is vertically and laterally adjustable by lifting and lining drives operated under the control of a leveling and lining reference system. This unit carries a power-driven, transversely and vertically adjustable lifting hook engageable with each rail and a pair of flanged lining rollers which may be pressed against the gage side of a respective rail by the lining drive. To enable the tamping operation to adjust to obstacles encountered along the track, particularly in switches, the ballast tamping units have tamping picks which may be laterally pivoted. This machine is adapted for universal operation in tangent track and track switches. It is furthermore adapted for continuous operation because the ballast tamping units as well as the track leveling and lining unit are mounted on a tool-carrying frame which is longitudinally displaceable with respect to the machine frame in the direction of the track, and a power drive longitudinally displaces the tool-carrying frame with respect to the continuously advancing machine frame so that the tool-carrying frame is held in a fixed position during each tamping operation. This non-stop operating machine type has revolutionized the track maintenance and rehabilitation technology since the separation of the machine frame from the tool-carrying frame has made it possible to permit the continuous advance of the heavy machine during the cyclic tamping operations only 20-30% of the entire machine mass being accelerated and decelerated between the tamping cycles while the vibrations resulting from the intermittent tamping are kept from the operating personnel riding on the continuously and evenly advancing heavy machine frame. This considerably enhances the comfort of the operators and, in addition, enables the machine to be used effectively even in difficult switch areas because the undercarriage supporting the tool-carrying frame on the track may be moved laterally onto the branch track as it branches off the main track at the beginning of the switch while the main frame remains on the main track.
U.S. Pat. No. 4,576,095, dated Mar. 18, 1986, also discloses a compact ballast tamping machine comprising two ballast tamping units respectively associated with a respective rail of a railroad track and mounted for independent, power-driven transverse adjustment. Each unit has two pairs of vibratory tamping tools reciprocable in the direction of the track and immersible in the ballast with a respective tie positioned between the tamping tools, a respective pair of each unit being arranged at the field side and the gage side of each rail, and each tamping tool has a double tamping pick connected to a power drive for independently vertically adjusting each double tamping pick. This enables each immersible tamping tool to be independently vertically adjusted to avoid an obstacle at either side of each rail.
U.S. Pat. No. 4,445,437, dated May 1, 1984, British patent application No. 2,201,178, published Aug. 24, 1988, and U.S. Pat. No. 3,426,697, dated Feb. 11, 1969, disclose switch tampers of the older, i.e. cantilevered, construction wherein the ballast tamping units are mounted on a projecting portion of the machine frame forwardly of the front wheels. They belong to a class of smaller tampers used mostly for spot tamping, and they are not equipped for track leveling and/or lining. Such machines cannot be used for accurate track position correction, including fixing the track in the corrected position.
The track tamper of U.S. Pat. No. 4,445,437 is equipped with two independent tamping units arranged on opposite sides of each track rail and each unit is mounted on a carrier frame for independent vertical and transverse adjustment, U.S. Pat. No. 2,587,324, dated Feb. 26, 1952 being acknowledged in the patent as prior art to show two tamping units arranged above each rail an transversely movable to permit tamping by displacement of the tamping tools with different operating strokes at the two sides of each rail. The tamping units are also vertically adjustable. In the illustrated embodiment, the four tamping units of U.S. Pat. No. 4,445,437 are connected to the machine frame by a lever system so that the transverse adjustment of each tamping unit simultaneously causes it to be pivoted about an axis extending in the longitudinal direction of the machine. The structure is rather cumbersome and requires considerable forces for pivoting the heavy tamping units.
In the tamping machine of British patent application No. 2,201,178, each of the four tamping units is individually vertically adjustable by its own power drive, two of the units being associated with each rail and each tamping unit having its own drive for transversely adjusting the unit on a guide frame. The machine is not equipped for track correction but in this class of cantilevered tampers it was conventional to mount track lifting and leveling tools, if any, in the projecting portion of the machine frame. With these outdated track leveling, lining and tamping machines, the track lifting strokes were quite limited and the track correction was relatively inaccurate. However, the requirements for track correction accuracy are particularly high in track switches, which are expensive, difficult to grip and quite heavy to lift and shift, and these requirements can be commercially met only with the above-described compact machines wherein the operating tools are mounted between widely spaced undercarriages.
The switch tamper of U.S. Pat. No. 3,426,697 has two vertically adjustable tamping units respectively associated with each track rail and independently transversely adjustable. These tamping units are mounted on a carrier frame which is cantilevered to the forward end of the machine frame and is pivotal by a power drive about a vertical axis and they are transversely displaceable along a transverse guide on the carrier frame so that the tamping tools may be adjusted to the varying spacing between the rails in track switches. This tamping unit arrangement is structurally complicated and does not enable the tamping tools to be accurately centered with respect to the tie to be tamped since the vertical pivoting axis is at a relatively great distance from the center of the transverse guide. This means that the tamping picks do not come to extend parallel to obliquely positioned ties in the switch so that proper tamping of the ballast under the ties is impossible.
U.S. Pat. No. 3,669,025, dated June 13, 1972, also deals with the same type of track tamper, and FIG. 17 of this patent illustrates ballast tamping units operable in switches and comprising hydraulically vibrated pairs of reciprocable tamping tools arranged at the field and gage sides of each rail. Each tamping unit may be vertically adjusted and the units or their pairs of tamping tools may also be independently transversely adjusted, as is more fully explained in column 4 of the patent in connection with the description of FIGS. 8-10 and 13. This enables the machine to operate without interruption or delays as the tamping tools encounter guide rails, frogs and the like. The spacing between the tamping units at each side of the rail may be adjusted since these units are transversely displaceably mounted on guide rails affixed, if desired, to a common carrier frame, as appears particularly from FIG. 13 showing four such transversely adjacent and mutually independently adjustable ballast tamping units arranged at the field and gage sides of each track rail. The tamping tools on one side of the rail or on both rail sides may form a structural unit with the carrier frame on which they are mounted, and this structural unit may be pivoted about a vertical axis extending in the plane of symmetry of this unit so that the tamping tools may be centered with respect to an obliquely positioned tie, as shown in FIGS. 12 and 17. While this makes it possible to compensate for a slightly oblique position of a tie and to adapt the positioning of the tamping tools to the tie position, the tamping picks will not extend parallel to the oblique tie.